1. Field of the Invention
The present invention relates in general to antenna support towers, and more particularly to antenna support towers having a foundation formed from prefabricated buildings.
2. Description of the Prior Art
Antenna support towers are tall, free-standing structures designed to carry communications antennae. The antennae are mounted at a height sufficient to provide broadcast capabilities over a large coverage area or for long distances for line-of-sight transmissions. Several types of towers are known in the prior art, including single-mast, multi-legged, and tapered monopole towers. Each tower has advantages and disadvantages ranging from cost to suitability of location site.
Typical installations for antenna support towers provide a prepared foundation for anchoring the tower to a support surface. For a single-mast tower, the entire tower may rest on one concrete foundation, the tower remaining upright through the use of radially-extending guy wires anchored to the support surface. A tapered monopole tower typically stands on a concrete column embedded in the support surface to act as a moment base for keeping the tower upright.
A multi-legged tower does not need guy wires to remain upright, instead having a base of at least three legs to transfer rotational loadings to the support surface. The support surface is typically concrete pads installed under each leg of the tower. In the case of each type of tower, a security fence is usually erected around the installation site.
Because of the installation requirements of prepared surfaces, fences, guy wires, etc., the time needed for a conventional tower installation is lengthy. Often, a tower needs to deployed quickly, but the typical installations do not permit rapid construction. Thus, there is a need for tower foundations that require less preparation of the site and reduce antenna support tower installation time.
The invention is an easily-constructed foundation for an antenna support tower. No fabricated support surface is needed at the installation site.
The foundation comprises a radial array of pre-fabricated buildings connected near their inner comers to each other. In a first embodiment, one leg of a multi-legged tower rests on each building, the buildings transferring forces from the tower to the support surface below the buildings. The buildings raise the base of the tower above the support surface, possibly negating the need for a fence around the installation site.
In a second embodiment, a tapered monopole tower is located in the center of the array of buildings. The monopole tower may sit on a prepared surface or may be supported above the support surface. The buildings are connected to each other at their comers, and support structures are attached at the same connection points, one support structure above the other. The support structures comprise a central ring and radially extending arms. The monopole tower is positioned within the central ring, transferring lateral loads through the ring and arms to the buildings. Guy wires are not necessary to keep the tower upright.